Statistics and Data Analysis Flashcards

A histogram shows data grouped into intervals. Which of the following CANNOT be easily determined from a histogram?

Answer: Exact individual data values

Histograms display grouped frequencies, so exact individual values within each interval are not visible.

A study finds that cities with more hospitals have higher death rates. Which conclusion is most appropriate?

Answer: Correlation does not imply causation

This is a classic example of a confounding variable (larger populations have both more hospitals and more deaths); correlation does not prove causation.

A researcher wants to survey 200 students about lunch preferences and randomly selects students from an alphabetical list at every 10th name. This is an example of:

Answer: Systematic sampling

Selecting every nth item from a list is the defining feature of systematic sampling.

A graph shows average income rising while the y-axis starts at $50,000 instead of $0. This technique is often used to:

Answer: Exaggerate the visual appearance of growth

Starting a y-axis above zero compresses the scale and makes small changes appear much larger than they really are.

A two-way table shows 120 students surveyed about pets. 60 own dogs, 40 own cats, and 20 own both. How many own neither?

Answer: 40

Using inclusion-exclusion: owners of at least one pet = 60+40−20 = 80; neither = 120−80 = 40.

In a normal distribution, approximately what percentage of data falls within one standard deviation of the mean?

Answer: 68%

The empirical rule states that approximately 68% of data in a normal distribution falls within one standard deviation of the mean.

A die is rolled 60 times. Based on theoretical probability, how many times would you expect to roll a 4?

Answer: 10

The probability of rolling a 4 is 1/6, so expected frequency = 60 × (1/6) = 10.